Image Transforming Device and Method Based on Edges

1. An apparatus for transforming an image, comprising: a linear interpolation block for generating linear interpolation information for an interpolation pixel to be interpolated between original pixels of a predetermined image; an edge information generating block for generating edge information which represents a pixel value of a pixel for indicating an edge and generating edge location information for indicating a location of an edge area of the image using two threshold values, within each of blocks consisting of the original pixel and interpolation pixel, respectively; a weight determining block for determining a weight for the linear interpolation information and the edge information of the interpolation pixel based on the edge location information; an interpolation information generating block for determining a pixel value of the interpolation pixel by reflecting the weight to the edge information and the linear interpolation information; and an interpolating block for generating the interpolation pixel based on the pixel value determined in the interpolation information generating block.

2. The apparatus as recited in claim 1 , further comprising an edge determining block for determining whether a predetermined block is an edge block that includes the edge surface, when the image is divided into a plurality of blocks, each comprising the original pixels and a predetermined number of interpolation pixels, wherein, if the block is not determined to be the edge block, the interpolating block generates the interpolation pixels based on the linear interpolation information.

3. The apparatus as recited in claim 1 , wherein the edge information generating block comprises: a threshold value determining unit for determining a predetermined upper threshold value and a predetermined lower threshold value; a primary edge information generating unit for comparing the linear interpolation information with the upper threshold value and the lower threshold value, and generating primary edge information for indicating pixel values of the pixels in the block and primary edge location information for indicating a location of a pixel that forms the edge surface; and a filtering unit for converting the primary edge information into the edge information by performing median filtering and transforming the primary edge location information into the edge location information based on the transformed edge information.

4. The apparatus as recited in claim 3 , wherein the threshold value determining unit calculates the upper threshold value and the lower threshold value based on an equation, which is expressed as: Th ⁢ ⁢ 1 = Max + Min 2 + α , Th ⁢ ⁢ 2 = Max + Min 2 - α , wherein Th 1 denotes the upper threshold value, Th 2 denotes the lower threshold value, Max and Min denote the maximum pixel value and the minimum pixel value among pixel values of adjacent pixels of an original pixel, respectively, and αdenotes an arbitrary constant.

6. The apparatus as recited in claim 5 , wherein the filtering unit determines a predetermined size of a window with a predetermined pixel of the block at the center, arranges primary edge information of each pixel of the window sequentially, and determines a median thereof as the edge information of the pixel.

7. The apparatus as recited in claim 1 , wherein the weight determining block determines a weight for edge information of each pixel in the block based on an equation which is expressed as: w = d ⁢ ⁢ 1 d ⁢ ⁢ 1 + d ⁢ ⁢ 2 , wherein w denotes a weight, and d1 denotes a distance to a non-edge block among adjacent blocks, and d2 denotes a distance to an edge area in the block.

8. The apparatus as recited in claim 1 , wherein the interpolation information generating block comprises: a first multiplier for multiplying the edge information by a first weight; a second multiplier for multiplying the linear interpolation information by a second weight; and an adder for adding operation results of the first multiplier and the second multiplier.

9. An image transforming method of an apparatus for transforming an image, comprising the steps of: a) generating linear interpolation information for an interpolation pixel to be interpolated between original pixels of a predetermined image; b) generating edge information which signifies a pixel value of a pixel for indicating an edge of the image and generating edge location information for indicating a location of an edge area of the image using two threshold values, within each of blocks consisting of the original pixel and interpolation pixel, respectively; c) determining a weight for the linear interpolation information and the edge information of the interpolation pixel based on the edge location information; d) determining a pixel value of the interpolation pixel by reflecting the weight to the edge information and the linear interpolation information; and e) generating the interpolation pixel based on the determined pixel value, wherein the steps are preformed by the apparatus.

10. The method as recited in claim 9 , further comprising: f) determining whether a predetermined block is an edge block that comprises the edge surface, when the image is divided into a plurality of blocks, each comprising the original pixels and a predetermined number of interpolation pixels, g) generating the interpolation pixels based on the linear interpolation information if the block is not determined to be the edge block.

11. The method as recited in claim 10 , wherein the step b) comprises the sub-steps of: b1) determining a predetermined upper threshold value and a predetermined lower threshold value; b2) comparing the linear interpolation information with the upper threshold value and the lower threshold value; b3) generating primary edge information for expressing pixel values of the pixels in the block and primary edge location information for expressing a location of a pixel that forms the edge surface; b4) converting the primary edge information into the edge information by performing median filtering; and b5) converting the primary edge location information into the edge location information based on the converted edge information.

12. The method as recited in claim 11 , wherein, in the step b1), the upper threshold value and the lower threshold value are calculated based on an equation, which is expressed as: Th ⁢ ⁢ 1 = Max + Min 2 + α , Th ⁢ ⁢ 2 = Max + Min 2 - α , wherein Th 1 denotes the upper threshold value, Th 2 denotes the lower threshold value, Max and Min denote the maximum pixel value and the minimum pixel value, respectively, among pixel values of adjacent pixels of an original pixel, respectively; and α denotes an arbitrary constant.

14. The method as recited in claim 11 , wherein the step b4) comprises the sub-steps of: b4-1) determining a predetermined size of a window with a predetermined pixel of the block at the center; and b4-2) arranging primary edge information of each pixel of the window sequentially, and determining a median thereof as the edge information of the pixel.

15. The method as recited in claim 9 , wherein, in the step c), a weight for edge information of each pixel in the block is determined based on an equation which is expressed as: w = d ⁢ ⁢ 1 d ⁢ ⁢ 1 + d ⁢ ⁢ 2 , wherein w denotes a weight, and d1 denotes a distance to a non-edge block among adjacent blocks, and d2 denotes a distance to an edge area in the block.

16. The method as recited in claim 9 , wherein the step d) comprises the sub-steps of: d1) multiplying the edge information by a first weight; d2) multiplying the linear interpolation information by a second weight; and d3) adding operation results of the step d1) and the step d2).